Authorities filed a murder charge Saturday against the alleged LAX gunman, Paul Anthony Ciancia, 23, and offered chilling new details that suggested the rampage was explicitly aimed at TSA agents.

The gunman was carrying a signed handwritten note in his duffel bag that said he wanted to “instill fear into their traitorous minds,” said David Bowdich, special agent in charge of the Counterterrorism Division at the FBI's Los Angeles office.

“His intent was very clear in his note,” Bowdich told reporters Saturday. “In that note he indicated his anger and his malice toward the TSA officers.”

A law enforcement official told The Times that the screed resembled a “suicide note.” The gunman said he didn’t want to hurt anyone “innocent” — only TSA agents. The note also mentioned “NWO,” a possible reference to the New World Order, a conspiracy theory that holds that forces are trying to create a totalitarian one-world government.

The shooter was apparently dropped off at LAX just after 9 a.m. Friday, authorities said, though they gave no details about the driver. The gunman wore dark clothes and a bulletproof vest and had not purchased a ticket. He carried a Smith & Wesson .223-caliber M&P-15 assault rifle, five loaded magazines and a trove of ammunition, Bowdich said.

After shooting Hernandez, authorities and witnesses said, the gunman calmly fired his way through the screening area, all the while cursing TSA agents. He asked terrified bystanders: “Are you TSA?” If they answered no, he moved on.

In a 10-minute spree that was captured on video, the shooter wounded two more TSA agents and injured at least one bystander, authorities said. Some travelers ducked behind planters and advertising kiosks to avoid gunfire; others fled to taxiing planes. Airport police, who were “60 seconds behind the suspect,” according to airport Police Chief Patrick Gannon, shot the gunman in the leg and head near a food court.

The accused shooter remains “unresponsive” at a local hospital, said authorities, who have been unable to interview him. In addition to murder, federal prosecutors charged him with committing violence at an international airport. If convicted, the suspect could face life in prison or the death penalty.

Meanwhile, Hernandez’s widow briefly addressed reporters, praising her husband as an ever-smiling father of two who came to L.A. from El Salvador at age 15 and joined the TSA three years ago. A neighbor said he routinely woke up at 3 a.m. to get to LAX on time.

“He was always excited to go to work,” said Ana Hernandez, who struggled to remain composed. “I am truly devastated.”

John S. Pistole, who oversees the TSA, joined Hernandez in front of the family’s Porter Ranch home. He said the unarmed TSA agents -- often derided in politics and pop culture as an airport nuisance -- were, in many respects, “the first line of defense” against violence.

He said the agency plans to reassess its policies, though he acknowledged “we can't guard against all threats and all risks.” J. David Cox, president of the union that represents 45,000 TSA employees, said airports should station armed security guards at each checkpoint and that it should be a federal crime to assault a TSA officer.

Investigators said they were combing Ciancia’s background for a possible motive. The unemployed motorcycle mechanic grew up in the Philadelphia suburb of Pennsville Township, N.J., where his father runs an auto body shop.

The success of Salem County Collision afforded the family beach vacations, private school tuition for their children and renovations to their stately home, said longtime family friend Alan Levitsky. Some of the work -- ramps and an elevator -- was done to accommodate a wheelchair for Ciancia’s mother, who suffered from multiple sclerosis, Levitsky said.